This invention relates to an apparatus and related method for testing soil for the presence of contaminants.
Industrial activity has lead to the deposition of many different chemical species in soil, some of which may be toxic to the local environment. Before large areas of soil are distributed, for example on a construction site, it is important to analyse the soil in order to ascertain the pollutants present. This is to avoid unnecessary or prolonged exposure to dangerous chemicals and/or to know how decontamination may be carried out.
Several methods of testing soil for pollutants are known. However, even within a relatively small area, pollutant levels may vary widely at different locations or different soils depths. Consequently, soil samples from a number of locations must be analysed, if a good assessment is to be made.
Known methods involve removal of a sample of soil which is then analysed at a laboratory. Analysis may be by a standard chemical method, in which the chemical pollutants are extracted and their structure and concentrations determined. Alternatively or additionally, the soil may be assessed by examining the bacteria present in a sample. A favoured method is to carry out a biological assay in which beetles, worms and the like are dissected and the level of chemicals absorbed in their tissues determined.
Such methods are involved and time-consuming, and in some cases may lead to inaccurate results. Collection of a soil sample disturbs the environment around which the sample is located. This in itself may lead to the sample being contaminated. For example, it may be difficult to obtain a sample from, for example, a meter below the surface without removing the soil above and thus changing the environment of the sample.
Once the sample is removed from its environment, the composition may change. Volatile components may evaporate: air sensitive moieties present may be oxidised or decomposition may occur during the interval between collection and analysis of a sample.
If a particular sample is found to be high in pollutants, it is often desirable to collect further samples from the surrounding area and at different depths so as to fully assess the extent of the pollution. This can often necessitate several trips to a site, which is expensive and inefficient.